Process of flattening glass sheets



Ketented dune 1?, 19240.

menu e. snmettrrr," announce PROCESS or 'nnn'rrnninej ms i f if V;

I inns-es W s n 1 19 Assamese i npplieation filed Ftruar ee ees serieind; $21,182: I

To all whom. it may concern" 1 l Be it known that l, Ilbuunp- Smmwm v a citizenof the UnitedqStates, andenresi dent of Mount Vernon, inthe- ,c0nnty0f e Knox and State of;;0hi0, have niadeza new: and useful invention in improvements in; Processes or". Elei'tening Glessl Sheets of which the following isiecaspecificationiw, The invention rc1ates1towag'iprocess for flattening glass "sheets, such 'esyer'e formed by drawing glass in cylinders andrsplittmg such as are formed in e continuously:opera-ting sheet glass machine in drawn in en approximatelyw'flatform but with suflicient departure from e'ltruexplane to render further fiatteningdesirable. Gless' thus produced I any substantial inerring of sucli surfaces in the fattening operation mustbeewided;

In the flattening of the semi cylindrica l sections produced by :the cylinder operation; it has been the practice to transfer wthe sec 1 tions to a flattening ovenhevingie' fiatten to". rotetewin horizontal H the "sections are placed 1 with the convex surfacesdownl- The heet 5 ing stone mounted plane upon which applied. to the oven is such asto 'softenythe. sections and the so flattened upon t e stones? by means oin flattening tool in the 'hendsof an operator;

The flattening of because of the handlabor, and the: surface of the glass next to the stone is often marred to e slight extent; it is the purpose 'of the present invention to avoid this 'objecsheet beingexazggemedl tion as to marring end to avoid the expense of the hand lehorin flattening; The proof 40 ess is also equally a pplicable to theflettem ing of the sheets producedinaxfsheetma chine in which the glass is drawn inilnt form. The glass as produced in zi machine of this sort, such as shownin myiepplicaticn, Serial No. 513,677, is approximetel'y flat and in the large number of cases is flat enough for glazing purposes, but it is desirable that a uniform flatness of 311 sheets should be secured and the present process has been foundsuitable for securing the necessary flattening at a small exense andwith a very slight ainount of realmge and with no substantial marring of the glass surface.

Briefly stated the nrocess is carried o bjn the use dofl,

cylinders into two sections and such-i which the glass is has fire finishedsurfeces and I are smoothed down" or" out} Figs. 2 "andB *aie sid thegless in" this way my volves a very considerable itemrotexpense" l vatio'n showing a slice "fro rn'l a sheet" suitable gearing tunnel kilnprouidedfwith carrying or transporting m ans {for the glass iin'the for-niof Ia series of -spaced" rollers arranged so that-the :glass ineybe fedinto' one aendofwtheflkiln and flattened during; itsipi'ogress theret'hi'ough on therollers'k "The heat applied et the entrance end of ens kiln is sufficientto soften theglassso that it? settles HClQVVIP" by? its own weight Q and flattens; upon [the rollers. Due tothe' fact th at the rollersare "roteting end" constantly" chengingl their lines iof' 'conta'ct' with the glass surface; there is no subst'entiiil nier' f ring off the surface' neXt tO the rolls, n1 though an I excess of teniperetu're ait this portion of the kiln would cause such mar ring 5 and: cause the sheets tds g between the I rollers. "The teniperetuies id the sue needing portions of the l iiln become-less and less softhatfithe" glziss'l'idits trevel" througlifl the kiln gradually burdens and anneals; and finallypasses f fr oln fthe outlet ends of the kiln m atem enure 't Web] the w in Fig. 3'i1nd2'nre"thesiilelivells bebiiided] with suitable openings burners "3 by lTlCiilllfidfWllldh the necessnyjhest Iney be secured: views seriesof rollers inou'nt," edl'transverselylofthe enddrivenjbvy f5 {'FiQJB) located outside the kiln. The rollsere preferabl abcut 4" in diameter and spaced out" centers. They may be made of materials specially designed to avoid marring the glass, such as nichrome or nickel or may be provided with carbon surfaces, but pyeferably they are of cast iron having their surfaces white washed or. covered with a film of rust, as this is it relatively cheep construction and ficient to secure proper flattening and annealingand permit of a reduction of temceeding sections chamber of t perature at the outlet end such that the sheets may be easily handled as they emerge. Asatisfactory temperature for the first section of'the kiln has been found to be about 1440" F. and the temperatures in the sucare successively lower, tapering down to about 200 F. inthe last section. In flattening the cylinder sections 8, as indicated at the left hand end of the -k1ln, these sections are placed upon the rolls twith their convex at Fig. 3. As the rolls 1n the first they quicklyhecome ture such that they lose their rigidity and settle down of their own Weight substantiallyflat as indicated at 9. v The constantly changing lines of contact between the glass and the rolls, however, prevents any suhsides'down as indicated sections are fed along the istanti'al marring, of'the polished surface,

and from; the point of emergence into the second chamber of the kiln, the tern erature is gradually reducedso that thesheet sets andreinains in almost perfectly fiat condition throughout its travel through the kiln, its temperature on emergence depending upon the length of the kiln employed and other conditions, but preferably being in the nei hborhood of 200 F. V

In app ying the process to sheets as formed in a sheet machine, andhaving a relatively sli ht amount of curvature, the pro cedure and temperatures employed are the same, the sheets being placed upon the rolls sit the left handend of the kiln and fed through the kiln as heretofore described. Upon the ap lication of heat in the first e kiln, the sheet 10 may in many cases warp very considerably as indicated in an exaggerated form in Fig. 4', but

this warping apparently imposes very little breaking strain upon the glass, as the breakage in carrying out the process is substarn tially negligible and the sheet soon reaches a temperature at which it is suificiently plastic to flatten itself upon the rolls. If there is any sagging of the sheet between the rolls when it is at its maximum temperature,

compartment of the kiln, heated to a temperav memos such sagging disappears as the temperature and it finally sets in a very flat condition; If the sheet is not perfectly annealed when it enters the kiln, it will become so annealed during its passage therethrough. i i

What I claim is:

1. A process of flattening sheets of glass having polished surfaces and'a curvature which it is desired to remove and in which the glass has a temperature below that at which it sets, which consists in movin the sheets continuously ahead in a heated 0 amher on spaced rotating supports to continuouslyshift the line of contact between the supports and the sheets, exposing the sheets to atemperature such as to cause them to soften and flatten of their own weight upon the supports but not sufiicient to cause any substantial marrinlg of the polished surfaces along the constantly shifting lines of contact with the supports, and. then exposing the sheets to progressively decreasing temperatures to permit them harden and anneal as they move fartheraiong. I

2. A process of flattening sheets of glass having polished surfaces and a curvature which it is desired to remove and" in which the less has a temperature below that at whie it sets, which consists in movin the sheet progresses along the rolls into an area of lower her on contantlv shifting points of support,

exposing the sheets to a temperature such as to cause them to flatten of their own Wei ht, and then exposing the sheets to progressively decreasingtemperatures to permit themto set as they move ,alon l 3. A process of flattening curved sheets of glass having a temperature below the setting point which through and having polished surfaces consists in conveying the sheets a tunnel. kiln having its highest temperature at the entrance end'and grad ually decreasing as the outlet end is approached and supporting the sheets upon rotating rolls, with the temperatures in the kiln adjusted in the entrance portion of the kiln. so that the sheet flattens of its own Weight but does not mar along the constantly shifting lines of contact ing supports.

Intestimony whereof, I have hereunto subscribed my name this 29th day of Jany.

I HARRY o; samenesswith the rotat- 

